[RFC PATCH 47/56] x86/module: Add ITS re-patch support for modules

David Kaplan
2025-10-13T14:36:23Z

When re-patching modules, call the appropriate functions related to ITS
mitigation support.

The ITS mitigation is unique because it requires memory operations that are
not possible under NMI context.

Signed-off-by: David Kaplan <david.kaplan@amd.com>
---
arch/x86/kernel/module.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index b6beb2b3469c..12a934755097 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -390,4 +390,36 @@ void arch_module_update_alternatives(struct module *mod)
apply_alternatives(aseg, aseg + alt->sh_size, mod);
}
}
+
+void arch_module_pre_update_alternatives(struct module *mod)
+{
+ const Elf_Ehdr *hdr;
+ const Elf_Shdr *sechdrs;
+ const Elf_Shdr *s;
+ char *secstrings;
+
+ if (!mod->klp_info) {
+ pr_warn("No module livepatch info, unable to update alternatives\n");
+ return;
+ }
+
+ hdr = &mod->klp_info->hdr;
+ sechdrs = mod->klp_info->sechdrs;
+ secstrings = mod->klp_info->secstrings;
+
+ for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
+ if (!strcmp(".retpoline_sites", secstrings + s->sh_name)) {
+ void *rseg = (void *)s->sh_addr;
+
+ its_init_mod(mod);
+ its_prealloc(rseg, rseg + s->sh_size, mod);
+ its_fini_mod(mod);
+ }
+ }
+}
+
+void arch_module_post_update_alternatives(struct module *mod)
+{
+ its_free_all(mod);
+}
#endif
--
2.34.1